The invention is directed to an apparatus for stabilizing a ladder in a desired position, and in particular to such an apparatus that is used to secure a ladder to a ferromagnetic surface, such as a metal storage tank.
Portable ladders, and in particular the leaning-type extension ladders usually constructed of aluminum or fiberglass, are well known in the art. Such ladders are commonly employed for many industrial applications where a worker much reach a relatively high area in order to perform, for example, painting or various maintenance, inspection, or repair operations.
In order to prevent slippage and resulting injury due to a fall, it is a common safety practice to tie or otherwise secure the top of a portable leaning-type ladder to the adjacent surface during its use. Workplace safety regulations promulgated by the United States Department of Labor's Occupational Safety & Health Administration (OSHA) require that these ladders be secured in certain workplace applications. OSHA estimates that of the portable ladder falls that result in injury or death, 61% occur from ladders that were not properly secured at the top. It is not always practical, however, to tie or secure the ladder to an adjacent surface. One common such application encountered is when a worker uses a portable ladder to reach a relatively high point on a large metal storage tank, such as are commonly used to store oil and other industrial liquids. Various points on these storage tanks must be reached for a number of reasons, including inspection, maintenance, and painting. The sides of these tanks are typically smooth, and contain no readily available means by which the top of a ladder may be secured. As a result, workers have no alternative but to use these ladders without securing them in place, which creates a significant safety risk for the worker. The risk to the worker is particularly great since painting and related work on a tank may require the worker to lean sideward from the ladder, increasing the risk that the ladder may slip during use.
It may also be seen that tying or other common means to secure the top of a portable, leaning-type ladder to a surface requires that a worker reach the top of the ladder before the ladder may be secured in place. Thus the worker is at risk until the worker reaches the top of the ladder and is able to complete the operation of securing the ladder in place. The movements necessary for the worker to secure the ladder in place may themselves lead to a slippage of the ladder, thus creating a risk associated with the very act intended to increase the safety of the further use of the ladder.
Another important safety issue with respect to the use of portable ladders is ensuring that the ladder is positioned at the proper angle with respect to the surface upon which the ladder is placed. OSHA Regulation 1926.1053(b)(5)(i) requires that leaning-type ladders be angled when in use such that the horizontal distance from the top support to the foot of the ladder is approximately one-quarter of the working length of the ladder. The working length is the distance along the ladder between the foot and top support. This ideal angle that results, with the ladder making an angle of about 76° with the horizontal support surface, maximizes the inherent stability of the ladder against slippage. When a portable ladder is in use in the field, however, it may be very difficult to determine whether the ladder is in fact properly positioned prior to use. The ease with which these ladders may be placed into position and the difficulty of determining the proper angle may encourage poor safety habits, particularly when the worker using the ladder is engaged in a time-critical maintenance operation.
It may be seen from the above discussion that an apparatus for stabilizing a portable ladder when there is no readily available surface to secure the top of the ladder in place would be highly desirable. A means of stabilizing the top of a portable ladder in place that does not require the worker to first climb the ladder would also be highly desirable. Finally, a simple, effective means of ensuring that the ladder is positioned at the optimum angle with respect to the surface upon which the ladder is placed would also be highly desirable. A device that combines these desired advantages would be of great benefit in improving the safety of using portable ladders in industry, particularly with respect to portable ladders used in locations where a tie-off at the top of the ladder is not practical.
References mentioned in this background section are not admitted to be prior art with respect to the present invention.